Process Capability Analysis of Additive Manufacturing Process through Predictive Model of Dimensional and Geometric Errors based on Machine Learning

, M.Sc. Thesis Sharif University of Technology Abdolahi, Alireza (Author) ; Khodaygan, Saeed (Supervisor)

Abstract

Additive manufacturing (AM)has gained extensive industrial and research attention in recent years. Reducing manufacturing waste, lead-time and costs and the ability to build surfaces and parts with complex shapes, assemblies all at once or parts with internal features are some benefits of AM. However, complex error generation mechanisms underlying AM digital physical chains are likely to result in geometrical inaccuracies of the final product, thus posing significant challenges to design and tolerancing for AM. Therefore, predictive modeling of shape deviations is critical for AM. With increasing volumes and varieties of data, machine learning has gained extraordinary popularity due to its...

Design and Implementation of an Iterative Learning Controller on Quadcopter Drone

, M.Sc. Thesis Sharif University of Technology Abdolahi, Yasin (Author) ; Rezaeizadeh, Amin (Supervisor)

Abstract

In this thesis, black-box identification, designing and implementing an iterative learning controller for the quadcopter was performed. Initially, the open-loop quadcopter system is unstable, so for black-box identification, a controller must first be implemented to stabilize it, but since no model is available from the system, the controlling parameters of the stabilizer through a proportional-integral and a proportional controller are executed as trial and error. To identify the roll and pitch models, the quadcopter is carried out using a radio controller and the measurements are saved during flight. Different models and methods are used to black-box identification, and finally the best...

Synthesis of mesoporous TiO2 structures through P123 copolymer as the structural directing agent and assessment of their performance in dye-sensitized solar cells

, Article Solar Energy ; Volume 133 , 2016 , Pages 24-34 ; 0038092X (ISSN) Abdolahi Sadatlu, M. A ; Mozaffari, N ; Sharif University of Technology

Elsevier Ltd 2016

Abstract

A novel and efficacious strategy was implemented for creation of mesoporous TiO2 films and powder through an integration of sol-gel and evaporation-induced self-assembly (EISA) processes aided by triblock Pluronic P123. A mesoporous crack-free thin film with virtual thickness of 300 nm was attained under 10% relative humidity aging, for 72 h at the low temperature of 5 °C. Further, the TiO2 film with porous structure has been formed from conventional paste, exploiting as-prepared mesoporous titania powder. The X-ray Diffraction (XRD) of synthesized mesoporous powder disclosed formation of anatase phase as well as rutile phase, in such a manner that the latter constituted a very small...

Direct synthesis of fixed-order multi-objective controllers

, Article Optimal Control Applications and Methods ; Volume 41, Issue 3 , 2020 , Pages 849-865 Abdolahi, A ; Babazadeh, M ; Nobakhti, A ; Sharif University of Technology

John Wiley and Sons Ltd 2020

Abstract

This paper introduces a new methodology for the design of fixed-order multi-objective output feedback controllers. The problem comprises a set of linear matrix inequalities and an additional rank constraint. The primary idea is to classify convex subsets of the set of rank constrained matrices in such formulations, based on which two noniterative and relatively fast methods are developed. The proposed methods require solving a convex optimization problem at each step and can be applied with any weighted summation of design objectives such as (Formula presented.) performance, (Formula presented.) performance, passivity, and regional pole assignment. Several benchmark systems with performance...

Wind farm power output optimization using cooperative control methods

, Article Wind Energy ; 2020 Deljouyi, N ; Nobakhti, A ; Abdolahi, A ; Sharif University of Technology

John Wiley and Sons Ltd 2020

Abstract

We study the application of cooperative control and game theoretic approaches to wind farm optimization. The conventional (greedy) wind farm control strategy seeks to individually maximize each turbine power. However, this strategy does not maximize the overall power production of wind farms due to the aerodynamic interactions (wake effect) between the turbines. We formulate the wind farm power optimization problem as an identical interest game which can also be used to solve other cooperative control problems. Two model-free learning algorithms are developed to obtain the optimal axial induction factors of the turbines and maximize power production. The algorithms are simulated for a...

Determination of the optimum conditions for recovery of gold from zarshuran refractory gold sulfide ore

, Article Iranian Journal of Materials Science and Engineering ; Volume 10, Issue 4 , 2013 , Pages 8-17 ; 17350808 (ISSN) Aazami, M ; Yoozbashizadeh, H ; Darban, A. K ; Abdolahi, M ; Sharif University of Technology

2013

Abstract

The orthogonal array design has been used to determine the optimum conditions for gold recovery from Zarshuran refractory gold sulflde ore (Iran) by direct cyanidation and roasting-cyanidation. The Taguchi method was used as the experimental design to determine the optimum conditions of dissolution behavior of gold with cyanidation and roasting-cyanidation from Zarshuran refractory gold ore. The experimental conditions were studied in the range of 10-12 for pH, 20-40 for time(h), 400-1200 for cyanide content (g/ton) and 30 -40 for percent solid(%). Orthogonal array (OA) L9 (34) consisting of four parameters each with three levels, was chosen. From this study for direct cyanidation the total...

Wind farm power output optimization using cooperative control methods

, Article Wind Energy ; Volume 24, Issue 5 , 2021 , Pages 502-514 ; 10954244 (ISSN) Deljouyi, N ; Nobakhti, A ; Abdolahi, A ; Sharif University of Technology

John Wiley and Sons Ltd 2021

Abstract

We study the application of cooperative control and game theoretic approaches to wind farm optimization. The conventional (greedy) wind farm control strategy seeks to individually maximize each turbine power. However, this strategy does not maximize the overall power production of wind farms due to the aerodynamic interactions (wake effect) between the turbines. We formulate the wind farm power optimization problem as an identical interest game which can also be used to solve other cooperative control problems. Two model-free learning algorithms are developed to obtain the optimal axial induction factors of the turbines and maximize power production. The algorithms are simulated for a...

Organoplatinum(ii) complexes containing chelating or bridging bis(N-heterocyclic carbene) ligands: Formation of a platinum(ii) carbonate complex by aerial CO2 fixation

, Article Dalton Transactions ; Volume 40, Issue 37 , Jun , 2011 , Pages 9362-9365 ; 14779226 (ISSN) Jamali, S ; Milić, D ; Kia, R ; Mazloomi, Z ; Abdolahi, H ; Sharif University of Technology

2011

Abstract

The preparation of two new bis(N-heterocyclic carbene) platinum(ii) complexes, in which NHC rings are joined by a CH2 linker group, is described. While, the chelate complex [PtMe2(bis-NHC1)], 1, was formed with large tert-butyl wingtips, the iso-propyl N-substituent analogue favors formation of the cluster complex [Pt2Me4(μ- SMe2)(μ-bis-NHC2)]2(μ-Ag2Br2), 2, in which two binuclear platinum(ii) complexes are linked together by an Ag2Br2 unit. The chelating platinum complex 1 undergoes aerial CO2 fixation and forms platinum(ii) carbonate complex [Pt(CO3)(bis-NHC1)], 3

The effect of major parameters on simulation results of gas pipelines

, Article International Journal of Mechanical Sciences ; Volume 49, Issue 8 , 2007 , Pages 989-1000 ; 00207403 (ISSN) Abdolahi, F ; Mesbah, A ; Bozorghmehry Boozarjomehry, R ; Svrcek, W. Y ; Sharif University of Technology

2007

Abstract

Predictions of the gas temperature and pressure profiles are vital to the design and operation of gas transmission lines. Available analytical methods for the calculation of these profiles are evaluated and a numerical framework for the rigorous calculation has been developed. The predictions from both the analytical and numerical procedure have been compared to field data from the Iranian Gas Trunk-lines (IGAT). These comparisons showed that all the available methods were tuned using data obtained from small to medium diameter pipes extrapolated poorly to large diameter pipelines. In order to improve the predictions for large diameter pipelines, the effect of model parameters such as soil...

Role of cooling rate in selective synthesis of graphene and carbon nanotube on Fe foil using hot filament chemical vapor deposition

, Article 2016 IEEE 7th Annual Ubiquitous Computing, Electronics and Mobile Communication Conference, UEMCON 2016, 20 October 2016 through 22 October 2016 ; 2016 ; 9781509014965 (ISBN) Abdolahi, M ; Kaminska, B ; Akhavan, O ; Talebi, S ; Ghoranneviss, M ; Arab, Z ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2016

Abstract

In this study, graphene sheets and carbon nanotubes (CNTs) were selectively grown on Fe foil at a relatively low growth temperature and varying cooling rates using a hot filament chemical vapor deposition (HFCVD) apparatus with C2H2 as the precursor. The results of the scanning electron microscopy and Raman spectroscopy revealed that the increase of the cooling rate from 7 to 10 or 20 °C/min provoked a structure transition from CNT to graphene. The optimum crystal quality of the graphene sheets (Iq/Id ∼1.1) was achieved at the cooling rate of 20 °C/min. According to the AFM analysis, the thickness of the stacked graphene sheets was found to be ∼2.9-3.8 nm containing ∼8-11 monolayers. The XRD...

Rcci Curvature for Metric-Measure Space via Optimal Transport

, M.Sc. Thesis Sharif University of Technology Taheri, Abolfazl (Author) ; Bahraini, Alireza (Supervisor) ; Ranjbar Motlagh, Alireza (Co-Advisor)

Abstract

One of the important questions in mathematics is generalized. In case of metric spaces, one of the questions is: Can we extend notions of Riemannian geometry to arbitrary metric spaces smoothly? Ricci curvature is one of the most important concepts in differential geometry. Ricci curvature is defined for the Riemannian manifold and has many applications in mathematics and physics like Einstein’s equation in relativity theory. There is a good notion for a metric space having “sectional curvature bounded below by K” or “sectional curvature bounded above by K”, due to Alexandrov. Can we define the concept of Ricci curvature in metric space? A motivation for this question comes from Gromov’s...

, M.Sc. Thesis Sharif University of Technology (Author) ; Khaloo, Alireza (Supervisor)

Abstract

Seismic design codes reduce loads by using response modification factor. Because of the reserved strength in structural elements and capacity of structure to dissipate energy, structures can be designed for lower seismic loads. This factor has modified over time. In this thesis, the effect of the reduction in behavior factor on the response of two kinds of reinforced concrete systems were evaluated. Moment resisting frames and dual systems with different heights and regularity in plan, heve been design according to the behavior factor which is recommended in the 3rd edition of the Iranian codes of practice for seismic resistance design of buildings (Standard No. 2800). Drift and...

Prediction of Financial Markets Using Combination of Artificial Intelligence and Technical Analysis

, M.Sc. Thesis Sharif University of Technology (Author) ; Haji, Alireza (Supervisor)

Abstract

Generally, nowadays, machine learning methods are used in many different areas for their superiority over other methods of prediction. Although being a tough task, stock market prediction with machine learning approaches is being spread due to satisfying results published ever yday. Machine learning methods usually use varied kinds of data ,including structured data such as market data, technical indicators and some fundamental data as well as unstructured one entailing text and graph data in order to enhance their predictability capacity. In this thesis we aimed to find out more about the importance and the contribution of structured data in prediction and we tried to attain a framework...

, M.Sc. Thesis Sharif University of Technology (Author) ; Hajji, Alireza (Supervisor)

Abstract

This thesis presents an inventory control system which is based on Meta-heuristic Algorithms.In this thesis we will optimize the input values of our tree-echelon inventory model (keeping costs,stock worth,reorder costs,...) with these Algorithms. The presented method is able to determine the optimal stock level, costs of system and number of shipments in the system. The method is basically a decision support system (DES) and it is able to provide the order scheduling parameters of goods at operational level. The aim of the current research is to demonstrate that a Meta-heuristic algorithmis capable of solving complex inventory problems and with future improvements it is able to achieve...

The Ricci Flow with Applications to the Poincare and Calabi Conjectures

, M.Sc. Thesis Sharif University of Technology Safdari, Mohammad (Author) ; Bahreini, Alireza (Supervisor)

Abstract

Poincare conjecture is one of the rst eorts for classifying 3-manifolds that was stated in the begining of 20th century. Eorts for proving this conjecture continued for about 100 years and nally Perelman has solved it in 2003. He has used Ricci ow which has been invented by Richard Hamilton in the early 80's. In this thesis rst we will introduce Ricci ow and will state the results before Perelman such as short time and long time existence of solution. Then we will mention some applications of Ricci ow and will state an explanation of the proof of uniformization and Calabi conjecture by Ricci ow. After that we start the main part of the thesis. In this part we will montion one of the...

Feasibility And Study(CNG Cylinder Production Plant)

, M.Sc. Thesis Sharif University of Technology Mousavi, Mohammad (Author) ; Haji, Alireza (Supervisor)

Abstract

Nowadays best using of fossil fuels sources of the country (and) importance of comparison against lack of capacity in petrol production make determined the programmers and the directors to foresee and design expanded programs of the goals, to use natural gas for car fuels. To reach fulfillment of these programs, the confirmed needs of the natural gas cylinders are improved and make it essential to invest on producing compressive natural gas cylinders. In this way economical and technical change researches has been done in order to construct on department to produce 200,000 compressive natural gas cylinders in a year during two sets.(shifts) According to the results of technical researches...

Synthesis, Characterization and Field Emission Study of Molybdenum Oxide (MoOx)Nanostructures

, M.Sc. Thesis Sharif University of Technology Khademi, Ali (Author) ; Moshfegh, Alireza (Supervisor)

Abstract

Different molybdenum oxide nano/micro structure thin films were synthesized by thermal evaporation method under various growth conditions such as deposition time, temperature and evaporation source-substrate distance. Molybdenum oxide nanostructures grown on Si(100) such as nanowalls, nanostars and nanowires were characterized with scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM). Shape and type of nanostructures were determined with SEM, AFM and HRTEM analysis. XPS analysis showed that the synthesized nanostructures contained Mo6+, Mo5+, Mo4+ and...

Identification and Abnormal Condition Detection of a Cement Rotary Kiln

, M.Sc. Thesis Sharif University of Technology Sadeghian, Masoud (Author) ; Fatehi, Alireza (Supervisor)

Abstract

One of the most important parts of a cement factory is the cement rotary kiln which plays a key role in quality and quantity of produced cement. In this part, the physical exertion and bilateral movement of air and materials, together with chemical reactions take place. Thus, this system has immensely complex and nonlinear dynamic equations. These equations have not worked out yet. Only in exceptional case; however, a large number of the involved parameters were crossed out and an approximation model was presented instead. This issue caused many problems for designing a cement rotary kiln controller. In this thesis, we employed a nonlinear system identification method for identification,...

Entanglement and Decoherence in Optomechanical Systems Coupled through Photothermal Effects

, Ph.D. Dissertation Sharif University of Technology Abdi, Mehdi (Author) ; Bahrampour, Alireza (Supervisor)

Abstract

Optomechanical systems have attracted considerable attention in the last decade. Such a raising prominence is mainly due to its capability in providing new insight into the quantum behavior of macroscopic objects and exploring the interface between quantum and classical mechanics. Alongside this fundamental quest, cavity optomechanics has many other benefits, ranging from very precise measurements on forces and positions to quantum information processing. In this thesis, we investigate quantum properties of such systems. Particularly, we study cooling of the mechanical resonator toward its ground state and the entanglement between this mechanical resonator and the cavity field. Cooling the...

Improvement in Reinforced Concrete Beam-Column Connections Behaviour using FRP Sheets

, M.Sc. Thesis Sharif University of Technology Rokrokian, Ali (Author) ; Khaloo, Alireza (Supervisor)

Abstract

Performance of reinforced concrete frames is highly dependent on detailing of the joint connections between its members, such as beams and columns. To have a good structural behavior, joints must show ductile behavior and designed based on the philosophy of strong column-weak beam. In the case of sever lacking ductility, strength or even rigidity of the connections, or having a weak column-strong beam, in the existing structures, there is a need for seismic upgrading of the connection. There are several ways for seismic upgrading of this type of connections.In the last decade Fiber Reinforced Polymer (FRP) widely has been used to strengthening the reinforced concrete (RC) members. Most of...